1. Field
The following description relates to disc defect management, and to a method of and an apparatus for managing disc defects using a defect management area (DMA) that can be updated, and a disc therefor.
2. Description of the Related Art
Defect management is a process of rewriting data stored in a user data area of a disc in which a defect exists. The data is rewritten to a new portion of the disc's data area, thereby compensating for the data loss caused by the defect. In general, defect management is performed using linear replacement or slipping replacement. In linear replacement, the user data area in which a defect exists is replaced with a spare data area having no defects. In slipping replacement, the user data area with the defect is marked, and data recording is slipped to a next user data area having no defects.
Both linear replacement and slipping replacement are applicable only to discs such as a DVD-RAM/RW, on which data can be repeatedly recorded and recording can be performed using a random access method. In other words, linear replacement and slipping replacement are difficult to apply to write once discs on which recording is allowed only once. In general, the presence of defects in a disc is detected by recording data on the disc and confirming whether or not data has been recorded correctly on the disc. However, once data is recorded on a write once disc, it is impossible to overwrite new data and manage defects therein.
After the development of CD-R and DVD-R, a high-density write once disc with a recording capacity of several dozen GBs was introduced. This type of disc can be used as a backup disc, since it is not expensive and allows random access that enables fast reading operations. However, defect management is not available for write once discs. Therefore, a backup operation is discontinued when a defective area, i.e., an area where a defect exists, is detected during the backup operation. In general, a backup operation is performed when a system is not frequently used, e.g., at night when a system manager does not operate the system. In this case, it is more likely that a discontinued backup operation will not be completed where a defective area of a write once disc is detected.